ZEF: Should the rest of the world go
it alone?
Tirpak: As a member of the secretariat, it is
not for me to say, this is a matter for the
Parties to decide. Mr. Pronk, President of
the Conference of the Parties, has launched
a catalogue of new ideas that will be discussed at a ministerial meeting the week after
Easter in New York. Later in the spring, there may well be additional consultations between governments. Hopefully, by the time
COP 6 resumes the USA will be able to come
forth with ideas of its own. At that time,
Parties will have to decide how they wish to
proceed
Nutrient Response Units
(NRU)
A Landscape Based Concept for
Sustainable Land Management in Uganda
Gerd Rücker, Soojin Park and Henry Ssali
Nutrient loss and soil erosion are
widely spread problems in
Uganda. A “landscape based”
nutrient management approach
shall help combat these problems.
The simple way of managing the fertility of the soil is to tailor technology to the
farmer’s abilities rather than to the needs of
his land. Such an approach is widespread
in Africa but ignores differences in land
quality (e.g., soil organic matter levels) and
soil fertility transfer (e.g., nutrient flows due
to erosion) within a landscape. A new way
In densely populated areas of
Uganda, such as the Lake Victoria Crescent and the Eastern
and South Western Highlands, soil nutrient resources
are being rapidly depleted.
This is mainly due to continuous cultivation coupled with
poor land management. As
farmers lack the financial
means, markets for input and
the knowledge of appropriate
land husbandry, there is little
or no replenishment of nutrients - neither with organic nor
inorganic fertilizers. Heavy
rainstorms cause rampant soil Nutrient loss through agriculture and erosion is one of
Photo: ZEF
erosion on slopes where vir- the most urgent problems in Uganda.
tually no soil or water conservation is practised. Farmers struggle with of targeting fertility management options
deteriorating land quality and are forced to within a landscape is being developed by
grow low nutrient demanding crops or aban- ZEF and the Kawanda Agricultural Redon highly degraded fields. Over the past search Institute (KARI) of the National Agthirty years this has led to a shift of banana ricultural Research Organization (NARO),
(Matoke) cultivation in favor of root crops Uganda. The objectives of the approach are
such as sweet potato and cassava within to assess spatially distributed soil nutrient
the Lake Victoria Crescent. Matoke cultiva- stocks and flows as well as soil fertility probtion has moved to the west. Farmers are also lems within a landscape. Site specific and
encroaching on wetlands in valleys and frag- socio-economic appropriate technologies
ile lands such as traditional grazing land on which integrate nutrient management and
hilltops. Since these lands have low resil- soil-water conservation are identified, testience, soil nutrients are being depleted at a ed and provided to agricultural extension
faster rate.
services for dissemination.
Landscapes in Uganda are complex,
comprising smallholder farming systems
with many small plots of different land use
on different aspects of the slopes. Patches
of land with similar nutrient stocks, flows
and soil fertility problems within the landscape are expected to respond equally to
integrated nutrient management and soil/
water conservation practices. Groupings of
such patches are defined as Nutrient Response Units (NRU) for which management
options are developed and fine-tuned according to the socio-economic conditions
of farm households. Last year a survey was
carried out in over 100 communities by the
ZEF-IFPRI research project on “Policies for
Improved Land Management in Uganda”.
Community resources were mapped, farmers were interviewed and soil samples analyzed to characterize soil fertility decline and
land management (see ZEF News No. 4,
May 2000). Out of this community sample,
two catchments have been selected for more
detailed NRU modeling.
With the help of farmers a plot survey
was conducted and data collected on the
spatial variation of land use and land management within each catchment. The socioeconomic conditions of farmers, such as
available land and labor were recorded during semi-structured interviews. Farmers also
guided ZEF researchers to assess their plant
nutrient resources and to map the flow of
nutrients on hillslopes. Soil fertility was further estimated by a systematic nested grid
soil sampling scheme. The Differential Geopositioning System (DGPS) was used to construct a digital elevation model and to
record plot boundaries. All data are stored
in a Geographical Information System (GIS).
This GIS is coupled with a mathematical
model to simulate nutrient flows across the
landscape. Spatial statistics and spatial
modeling are then applied to demarcate
Nutrient Response Units as homogenous
landscape patterns.
The NRU concept is being developed
jointly with a local agricultural extension
agency and farmers to ensure that it can be
easily adopted. This participatory approach
will facilitate dissemination of integrated
nutrient management technologies at catchment scale, which can be targeted both to
the NRU specific needs of land as well as to
the socio-economic capability of smallholder farming systems, thus stabilizing or improving soil resources of all landscapes for
sustainable food production.
Gerd Rücker and Soojin Park are
research fellows at ZEF, Department
“Ecology and Resource Management”. Henry Ssali is senior researcher at the Kawanda Agricultural Research Institute in Uganda.
ZEFnews No. 7 May 2001
7